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SUMMARY:Probing Chemistry at the Ångström-Scale via Scanning Tunneling M
 icroscopy and Tip-Enhanced Raman Spectroscopy - Associate Professor Nan Ji
 ang\, Department of Chemistry\, University of Illinois Chicago\, USA
DTSTART:20230615T140000Z
DTEND:20230615T150000Z
UID:TALK200788@talks.cam.ac.uk
CONTACT:Julie Smith
DESCRIPTION:My research group is interested in investigating how local che
 mical environments affect single-molecule behaviors with Ångström scale 
 resolution. This talk will start with Tip-Enhanced Raman Spectroscopy (TER
 S)\, which affords the spatial resolution of traditional Scanning Tunnelin
 g Microscopy (STM) while collecting the chemical information provided by R
 aman spectroscopy. By using a plasmonically-active material for our scanni
 ng probe\, the Raman signal at the tip-sample junction is incredibly enhan
 ced\, allowing for single-molecule probing. This method\, further aided by
  the benefits of ultrahigh vacuum\, is uniquely capable of controlling loc
 alized plasmons via an atomistic approach. We are able to obtain (1) singl
 e-molecule chemical identification\;1 (2) adsorbate-substrate interactions
  in the ordering of molecular building blocks in supramolecular nanostruct
 ures\;2 (3) atomic-scale insights into the oxygen reactivity of 2D materia
 ls\;3(4) local strain effects in an organic/2D materials heterostructure.4
  By investigating substrate structures\, superstructures\, 2D materials la
 ttices\, and the adsorption orientations obtained from vibrational modes\,
  we extract novel surface-chemistry information at an unprecedented spatia
 l (< 1 nm) and energy (< 10 wavenumber) resolution. Another application of
  localized surface plasmons is to achieve site-selective chemical reaction
 s at sub-molecular scale. We recently selectively and precisely activated 
 multiple chemically equivalent reactive sites one by one within the struct
 ure of a single molecule by scanning probe microscopy tip-controlled plasm
 onic resonance.5 Our method can interrogate the mechanisms of forming and 
 breaking chemical bonds at the Ångström scale in various chemical enviro
 nments\, which is critical in designing new atom- and energy-efficient mat
 erials and molecular assemblies with tailored chemical properties.\n\nRefe
 rence:\n1. S. Mahapatra\, Y. Ning\, J. F. Schultz\, L. Li\, J. -L. Zhang\,
  N. Jiang\, “Angstrom Scale Chemical Analysis of Metal Supported Trans- 
 and Cis-Regioisomers by Ultrahigh Vacuum Tip-Enhanced Raman Mapping”\, N
 ano Letters\,19\, 3267-3272 (2019).\n\n2. J. F. Schultz\, L. Li\, S. Mahap
 atra\, C. Shaw\, X. Zhang\, N. Jiang\, “Defining Multiple Configurations
  of Rubrene on a Ag(100) Surface with 5 Angstrom Spatial Resolution via Ul
 trahigh Vacuum Tip-Enhanced Raman Spectroscopy”\, The Journal of Physica
 l Chemistry C\, 124\, 2420-2426 (2020).\n\n3. L. Li\, J. F. Schultz\, S. M
 ahapatra\, X. Zhang. X. Liu\, C. Shaw\, M. Hersam\, N. Jiang\, “Probing 
 interfacial interactions in an organic/borophene heterostructure with angs
 trom resolution”\, Journal of the American Chemical Society\, 143\, 38\,
  15624-15634 (2021).\n\n4. L. Li\, J. F. Schultz\, S. Mahapatra\, Z. Lu\, 
 X.  Zhang\, and N. Jiang\, “Chemically identifying single adatoms with s
 ingle-bond sensitivity during oxidation reactions of borophene”\, Nature
  Communications\, 13\, 1796 (1-9) (2022).\n\n5. S. Mahapatra\, J. F. Schul
 tz\, L. Li\,  X. Zhang\, and N. Jiang\, “Controlling Localized Plasmons 
 via an Atomistic Approach: Attainment of Site-Selective Activation inside 
 a Single Molecule”\, Journal of the American Chemical Society\, 144\, 5\
 , 2051-2055 (2022).\n
LOCATION:Goldsmiths 2 &amp\; https://us06web.zoom.us/j/81688365420?pwd=b3R
 pdHgxNVhWbWQrbXluMUxYNWVtQT09 Meeting ID: 816 8836 5420 Passcode: 047859
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